In situ deposition of epitaxial PZT films by pulsed laser deposition

Pb(Zr_xTi_1-x)O₃ (PZT) thin films were in situ-grown on Pt/Ti/SiO₂/Si substrates by a hybrid process consisting of the sol-gel method and pulsed-laser deposition (PLD). The deposition temperature to obtain the perovskite phase in the hybrid process is 460°C, and is significantly lower than that in the case of direct film deposition by PLD on a Pt/Ti/SiO₂/Si substrate. X-ray diffraction analysis indicated that the preferred orientation of PZT films can be controlled using the layer deposited by the sol-gel method and highly (111)- or (100)-oriented PZT films were obtained. A transmission electron microscopy (TEM) image showed that the film had a polycrystalline columnar microstructure extending through its thickness, and no sharp boundary was observed between the layers deposited by the sol-gel method and PLD. A high-resolution electron microscopy image and electron diffraction analysis revealed that the crystalline lattice of the layers deposited by the sol-gel method and PLD was continuous and there was no difference in crystalline orientation between the layers. These results indicate that the solid-phase epitaxial effect between the PZT layers deposited by the sol-gel method and PLD decreases the deposition temperature to obtain the perovskite phase during PLD, and causes the films to exhibit the same preferred orientation as that of the layer deposited by the sol-gel method. The dielectric constant and remanent polarization of the films in situ deposited at 460°C were approximately 900 and 15 μC/cm², respectively.